• Blogs
• Forums
• Tradeshows
• Partners
• White Papers
• Events

 

Mummy Reboot

Jul 1, 2008 11:00 AM, By Michael Goldman

Rob Cohen steers franchise's visual effects in a new direction.

Both companies animated the emperor mummy at various times, each facing the challenge of how to evoke the familiar and distinctive movements of Li. This challenge was further complicated by the fact that Li's availability to the production was severely limited due to a scheduling conflict, thus limiting the filmmakers' ability to run him through detailed motion-
capturesessions.

“We had him scanned and all that, but the character's movement is largely from pure imagination,” Cohen says. “The original idea was that the clay would have this basic blankness that true terra-cotta [statues] have. In other words, the eyes are not articulated. But we had to rig the face to have total expressiveness. So the scan and Jet Li's vocal performance [and video reference] were key to getting us the reference we needed.

“To be honest, [the actor] was only available for one scene in which he played a terra-cotta warrior. But I felt it was better to make him a CG character for the middle part of the movie anyway, because no matter how good makeup might be, he wouldn't have the same power for what we had in mind that a true CG creation would have,” Cohen says. “So that is how the idea that he was two characters got developed. He had a clay terra-cotta warrior shell and the real burned and disfigured character underneath.”

Among other techniques, for close-up shots of Li's emperor mummy, Digital Domain used the so-called “witness-cam” technique. Essentially, the company used two HD witness cameras to film his face during principal photography while Duggan's unit was recording him with a film camera. This gave filmmakers Li's facial performance from two wide angles (almost 45 degrees apart). Company artists were then able to take the HD footage and sync it together with the primary film camera's footage to produce three distinct views of his facial movements.

“Then, using our proprietary [Sci-Tech Award-winning] tracking software [dubbed ‘Track’], we were able to identify and track unique features through each of these cameras,” Butler says. “For example, we could locate Jet Li's right eye as one point, visible through all three cameras, and then use triangulation to give us an accurate 3D location for that point in space relative to the main camera. After locating several of these points through each camera, we were able to accurately constrain a model of Jet Li's head to the main camera image. The addition of two extra views of the action allows us to ensure that the 3D position of the CG Jet Li was accurate on [scenes such as] when mud is flowing from his eyes and nose.”

Tools and techniques

The texture and general look for the terra-cotta mummies, according to Cohen, was meant to evoke “a liquid-solid approach in which the terra cotta cracks at certain stress vectors that would happen when force was applied, and then there is a sort of molten generation of terra cotta that reseals it. That infinite amount of cracking and re-sealing creates the terra-cotta look. So the emperor and the terra-cotta army work on a slightly different set of aesthetics,” Cohen says.

It's not only the terra-cotta army that awakens from the dead, but also their horses, which crack out of their own bronze shells at one point. According to Rhythm & Hues' Spears, the presence of different kinds of shells presented filmmakers with the question of exactly how their fragile exteriors should crack.

“There's two types of cracking really,” Spears says. “The terra cotta has a different type of crack than how metal would crack. Terra cotta has more of a clay fracture, resulting in ragged edges. That work was largely done by Digital Domain, and then we re-implemented it with our own internal systems. Then, we had a different type of cracking for [horses]. Both approaches are meant to relieve stress, so that they wouldn't have stretching textures or look like they were made of rubber. But the horses are made of bronze, and therefore have a crisper crack. It's a more subtle differentiation, but we built our systems to allow a little give and take between stretching and cracking, so that it wouldn't look like a collection of spare parts running around and would retain some shape coherency. Our internal system essentially does collision detecting and then cracking based on stress factors. Those are actually brand-new tools we developed on this show — an extension of some of our cloth and physical systems that are built into our animation software.”

Digital Domain and R&H usedAutodesk Maya on the project. Digital Domain used Side Effects Houdini for procedural-based, natural-phenomenon-type effects and Nuke, the compositing package originally created at the company, as well as its Track software and its Storm volumetric rendering package. Rhythm & Hues, meanwhile, also relied on its own suite of proprietary tools, including its Ren internal rendering technology and its Icy compositing system.

Another familiar tool also played a key role during the climactic battle between rival armies of dead Chinese warriors. That tool, of course, is the famous Massive AI software that is used for animating large crowds in an organic way. That technology, first made famous on the Lord of the Rings trilogy, is still doing its thing quite nicely for applications such as the battle scene in The Mummy: Tomb of the Dragon Emperor, Hynek says. Digital Domain was able to create “quite a sophisticated brain” for manipulating the warring armies.

“It was my first foray into Massive, actually,” Hynek says. “But it was astounding to see scenes come alive with it. The thing about it is you don't know what it will look like when you put the parameters in there. The actions it came up with for both armies were quite startling, largely because it is so unpredictable. The hard part is building the brain — that took us many months. But, once you do that, they really start rolling nicely off the conveyer belt.”

Building that brain, however, is no simple task, Butler says.

“You have to design the options, and decide what to go out and capture and add [to the artificial intelligence],” Butler says. “We did research; we did video shoots; we went to Montreal where they were shooting and got behavioral characteristics from some of our actors. From all that, we built a familiar tree of points that the brain could feed from. Then, you find out what the director wants for a particular scene when you get there, and you might augment things with some very specific mo-cap animation or hand animation if you need to, and then you can achieve all those shots. It's pretty powerful what it can do.”

With the production taking place in Canada and China; the editorial happening (incorporating Avid Media Composer Adrenaline HD's DNxHD 36 codec) in Los Angeles; film being transferred at Technicolor in Burbank, Calif.; the visual-effects process ongoing at the two Los Angeles-based facilities; and dailies and the digital-intermediate process happening at Company 3,Santa Monica, Calif., there were — understandably — lots of IT issues to grapple with in moving data around. But just as important, the filmmakers say, was having a common approach for viewing dailies imagery at these disparate stops along the workflow highway. Duggan, in consultation with Cohen, took charge of distributing a common template for the basic color palette as a first step in this process.

“During the shoot, I took hundreds of digital reference stills of each scene, simply grading them in Photoshop and distributing them each day to Rob Cohen, the dailies colorists, and the visual-effects teams,” Duggan says. “Rob was happy with how it looked, so this gave everyone a fairly clear visual direction. In Montreal, the crew watched projected HD dailies, and the quality was great for technical checks such as focus and makeup. In China, we were unable to turn dailies around fast enough, so Company 3 set up a password-protected link to their server so we could access any of our dailies at any time.”

The look-up table (LUT) component to make sure that what was being viewed at different locations remained consistent on the various 2K projectors used at the different facilities was Filmlight's TrueLight color management and calibration system.

“That was important — both effects companies and Company 3 got together to work out a common format and platform so that we all had a common LUT and viewing environment to see how our digital images will look on film,” Butler says.

Cohen collaborated with colorist Stefan Sonnenfeld at Company 3 to establish the final color of the piece, because Duggan was off shooting another film during the DI. For the most part, the color template for sequencesranging from the snow-coveredHimalayas to warm, desert battlefields to the streets of Shanghai were well-established during the dailies process.

But Cohen, like many of his contemporaries, says he was thrilled with the DI experience on this project, and ingeneral.

“The idea that we used to sit in a screening room with a timer, and as the film unspoiled, we yelled ‘quarter point cyan,’ or ‘I don't want the green,’ and by the time we did one note, six to eight shots had gone by — I mean, it was primitive,” he says. “And I was doing it that way as recently as The Fast and the Furious [in 2001]. I did my first DI with xXx [2002]. Now, we can define a wall, take off some rim light, open up someone's face, shift that person more toward gold — you can make infinite moves on the image; you can virtually relight it. So, I don't miss smelling those chemicals — I have no nostalgia for it whatsoever.”

© 2009 Penton Media, Inc.